In recent years a number of international treaties and agreements have committed nations around the world to reduce their weapons arsenals. For example, in January 1993, representatives from more than 130 nations signed the final draft of the Chemical Weapons Convention, which outlaws the production, use, sale, and stockpiling of all chemical weapons and their means of delivery and calls for the destruction of existing stocks by the year 2005. In 1993, some 20 nations were suspected of possessing chemical arsenals or having the means to make them.
A patent application, in the name of the assignee of the instant application, has been filed under the Patent Cooperation Treaty and discloses a chemical method and apparatus for destroying chemical warfare agents ("CWA's" hereinafter); that is, application PCT/US96/16303, filed Oct. 10, 1996 and incorporated herein by reference. That method utilizes nitrogenous base, optionally with active metal, in a dissolving metal reduction.
In most cases CWA's are stored in munitions that also contain energetic materials ("EM's" hereinafter). The U.S. Army's M-55 rocket, a chemical warfare weapon, is an example. In this weapon, leakage of the nerve agent "Sarin" or "GB" into the burster charge has already been observed, and it has been noted that the rocket's propellant is also becoming unstable. The "M-28" propellant in the M-55 rocket is a mixture of nitrocellulose, trinitroglycerine, binders, and stabilizers. The burster charge, which disperses the nerve agent upon rocket impact, is an explosive mixture comprising trinitrotoluene ("TNT") and cyclomethylenetrinitramine ("RDX"), otherwise known as "Composition B."
Whereas, a means for destroying the CWA's was provided in the referenced earlier application, a serious problem remains; namely, it remains to provide a method for demilitarizing the explosives and/or propellants used to deliver the CWA's to their targets and disperse the CWA's once the targets are reached.
The instant application addresses this outstanding problem by providing a method for destroying the EM's incorporated into the explosives and/or propellants used as delivery means for the CWA's. With considerable surprise, applicants have found, quite unexpectedly, that the method earlier disclosed to substantially destroy the CWA's can also be employed to substantially destroy the EM's contained in the delivery means which accompany the CWA's. This serendipitous discovery not only greatly simplifies the destruction of the complete package of hazardous substances accompanying and including the CWA's, but also provides an attractive method for destroying EM's outside the CWA context as well. Aside from the CWA context, EM's are employed by military and civilian organizations, as well as individuals, in weapons of various kinds, including the small arms ammunition used by hunters, as well as in various blasting operations, including mining, and so forth. In another context, EM's appear as soil contaminants at a number of hazardous materials sites, and the method of this invention can often be advantageously employed in the remediation of those sites.
EM's are components in three classes of products, namely, explosives, propellants, and pyrotechnics; see, for example, Department of the Army Technical Manual TM 9-1300-214, "Military Explosives," Headquarters, Dept. of the Army, 1984 and the manual provided at "An Introduction to Explosives," presented at the FAA's Energetic Materials Workshop, Avalon, N.J., Apr. 14-17, 1992. The EM's in explosives and propellants, when chemical reaction is properly initiated, generate large volumes of hot gases in a short time, the primary difference between propellants and explosives being the rate at which the reaction proceeds. In explosives, a fast reaction produces a very high pressure shock wave which is capable of shattering objects. In propellants, a slower reaction produces lower pressure over a longer period of time. Pyrotechnics evolve large amounts of heat but much less gas than explosives and propellants.
In general, the burning or detonation of products containing EM's involves exothermic redox chemistry. Whereas, the instant invention can be applied to the destruction of certain components of pyrotechnic compositions, it is more profitably applied to the destruction of EM's included in compositions which function primarily as explosives and/or propellants. The method of this invention, while applicable to the destruction of conventional explosive or propellant delivery means which may be a part of nuclear weapons, is not applicable to the destruction of the nuclear weapons themselves.
According to TM 9-1300-214, cited above, most EM's contained in weapons cannot be safely disposed of by dissolving them in water and treating the solutions as sewage, because they are generally insoluble in water, are often toxic, and are hazardous to the environment. It is said that disposal must be by burning, detonation, or chemical decomposition. Although elaborate precautions are mandated for disposing of even small quantities (grams) of EM's by burning or detonation, no other general methods of destruction by chemical means are set forth.
Reclamation of EM's using hot water or steam, for those EM's which melt, has been recommended. Trinitrotoluene (TNT), for example, can be melted by contact with boiling water or steam and thereby extracted from the warhead or other device in which it is found. The extraction is followed by precipitation with cold water. TNT can also be reclaimed by dissolution in, for example, benzene or xylene, followed by evaporation of the solvent. Many other EM's are not so readily reclaimed.
Explosive and especially propellant compositions can comprise complex mixtures of various inorganic and organic chemical compounds, as well as discrete, physically separate components in an explosive or propellant train. Various additives may be incorporated into the composition along with the EM's, for example, to control shock-sensitivity or, especially in the case of propellants, to maintain the flame temperature within a certain range and to achieve the maximum energy output given that temperature limitation.
The redox reactions of EM's are generally initiated in a small quantity of shock-sensitive primary explosive or primer using mechanical, electrical or thermal means, the primer in turn triggering a booster or secondary high explosive, which represents the largest EM component of the charge. Nitrogen-containing compounds are by far the most common EM's employed in booster and secondary charges, and many of them are inorganic nitrates and organic nitro compounds. However, the frequent incorporation into explosives and propellants of compounds which are neither nitrates nor organic nitro compounds, for example, the metal salts used as primers, has made it heretofore impossible to devise any chemical process sufficiently universal in its application that it can be trusted to destroy whatever EM or mixture happens to be present without the substantial risk of explosion.
Dissolving metal reduction chemistry is not new; it is embodied in the well known "Birch Reduction," which was first reported in the technical literature in 1944. The Birch Reduction itself is a method for reducing aromatic rings by means of alkali metals in liquid ammonia to give mainly the dihydro derivatives; see, for example, "The Merck Index," 12th Ed., Merck & Co., Inc., Whitehouse Station, N.J., 1996, p. ONR-10.
Such dissolving metal reductions have been the subject of much further investigation and numerous publications. Reviews include the following: G. W. Watt, Chem. Rev., 46, 317-379 (1950) and M. Smith, "Dissolving Metal Reductions," in "Reduction: Techniques and Applications in Organic Synthesis," ed. R. L. Augustine, Marcel Decker, Inc., New York, N.Y., 1968, pages 95-170. Dissolving metal reduction chemistry is applicable to compounds containing a wide range of functional groups.
For example, alkylnitro compounds can be reduced to the corresponding alkylhydroxylamines with sodium and liquid ammonia; see M. Smith, cited above, p. 115, and aromatic nitro compounds can be reduced to the corresponding amines with a lithium/amine reagent; see, R. Benkeser and coworkers, J. Am. Chem Soc., 80, 6593 (1958) and G. Watt, cited above, p. 356. The overall reaction from --NO.sub.2 to --NH.sub.2 requires 6 moles of active metal, for example Na, per mole of --NO.sub.2 ; 2 moles of metal per mole of .sub.2 -NO produce the corresponding hydroxylamine, --NHOH. Dinitrocellulose is reported to yield an amine derivative when treated with sodamide in liquid ammonia; see P. Scherer and coworkers, Rayon Textile Monthly, 28 72 (1947); CA 2101f (1948). Very little technical literature is available which describes the dissolving metal reduction of compounds with more than one nitro group.
It is well known that most chemical reagents are species-specific; that is, a chemical reagent generally reacts with a substance having a certain specific functional group. An acid reacts with a base, much less commonly with another acid. An oxidizing agent reacts with a reducing agent. With such species-specific chemistry, destruction of an EM would seem to require one to first establish the identity of the EM or the mixture of EM's to be destroyed in order to select the right reagent or combination of reagents to react with that particular material.
Operationally, traditional chemical processing, as envisioned in the past, would frequently require handling and transferring of EM's by human operators. Such handling operations could include, for example, removal of the EM-containing explosive or propellant from a warhead or missile casing, canister or other containerized delivery system, thereby exposing personnel to the grave danger of contact with the EM. Loading the EM-containing material so-removed from its container into a separate reaction vessel would lead to another opportunity for exposure to the EM.
Finally, traditional chemical methods which might be proposed for the destruction of EM's would undoubtedly have high capital requirements for equipment, facilities, and personnel safeguards, as well as requiring time-consuming, labor-intensive processing. Then, there is the further cost of disposing of the products after the EM destruction chemistry has been carried out. In light of all this, one can understand why, compared against such chemical treatments, incineration or detonation of the EM-containing compositions, producing water, carbon dioxide and inorganic salts (ideally), has seemed relatively attractive.